A cyclonic separator was disclosed in U.S. Pat. No. 3,392,513, Hedin, with a spiral inlet portion and exit (for clean gas) with discharge dampers for emptying dust collecting bins which thereby permits continuous operation of the separator. In 1980, U.S. Pat. No. 4,205,965 issued to Bielefeldt for an apparatus for eliminating dust particles from a gas having a lighter density than the particles. Essentially, the admixture is charged to a bent channel and partially introduced into a whirling chamber which takes advantage of primary eddy flows, circular secondary eddy flows and sink flows. The primary eddy flow is accelerated approximately 300 times the acceleration created by gravity by the combination of a tangential curved wall through the flow channel extending over the entire chamber height. The concentrated sink flow is maintained in the central portion of the whirling chamber and is substantially localized due to suction pipes in communication with operative fans. Two U.S. patents issued to Bieth, U.S. Pat. Nos. 2,103,809 and 1,953,948, disclose an apparatus which utilizes angular velocity of solid particles to separate the same from a gaseous material. Essentially, the gas is charged to a circular flow path in admixture with the solid materials, which during acceleration are transmitted to a trench overlaying a conical funnel. The gases continue throughout the apparatus and exit therefrom through a longitudinal situated outlet port.
In Visman, U.S. Pat. No. 3,366,247, a cyclonic apparatus is disclosed wherein solids charged to the cyclone are separated from a gas by imparting to the suspension centrifugal accelerations or the order of 300 to 400 times the acceleration of gravity. A feed inlet pipe communicates tangentially with the separation chamber which contains a tubular vortex finder. The granular materials fall to the bottom of the cyclone separator while an overflow discharge pipe extracts water flow separated from the granular material. In Latham et al U.S. Pat. No. 3,177,634, an apparatus is disclosed for the recovery of solids from gas in which a deflector cone separates a helical gas stream to cause fluid droplets to be deflected against the wall of the cyclone separator and thereby removal of the fluid gases through louvers situated in a direction opposite in flow from the helical gas motion.
In Evans U.S. Pat. No. 2,888,096, a horizontal centrifical separator is disclosed wherein primary mass separation and secondary cylindrical separation are utilized within a horizontal cyclone separator (but absent an inclined slot solid dropout means interconnecting the upstream portion of the horizontal cyclone separator and a vertical downcomer attached to the relative opposite end or downstream end of the cyclonic separator). See also Evans U.S. Pat. No. 2,901,420. In U.S. Pat. No. 4,455,220, Parker et al, catalyst and hydrocarbon vapors are separated in a vertical cyclone separation zone by use of a vortex stabilizing means which separates the cyclone zone from the stripping zone and allows stripping gas from the stripping zone to be passed upwardly into the cyclone zone countercurrent to the downflow of separated catalyst. This improves both the separation and stripping of the gaseous hydrocarbons from the separated catalyst and reduces the catalyst hydrocarbon contact time, thereby improving gasoline yield and olefin content.
The instant invention is an improvement upon the Parker et al apparatus because it possesses a higher tolerance for the backflow of stripping gases and eliminates the necessity for a right angle turn atop the riser reactor feeding the applicable cyclonic separation device. In addition, the instant cyclonic separation device attains fast separation of heavy solid loaded-admixtures in the very front part of the cyclone separator, which results in the downstream or secondary centrifugal separator operating in a light load manner despite the initial high inlet loadings of the cyclonic separator. The prior art fails to recognize the combinative primary mass flow and secondary centrifugal separation mechanisms with the inclined slot solid dropout means to pass the majority of the catalyst therethrough to the bottom of a downcomer vertical conduit interconnecting a stripping zone at the other extreme.